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I've created a PCB design for the first time ever, but I would like to know if I've made any mistakes that will result in a broken board or short circuits in the near future. I've encountered people on numerous questions that would like to help in making sure that a PCB is correctly designed and that a "person in this job situation" would love to check it out.

Schematic enter image description here

PCB (blue is bottom, red is top) enter image description here

I would really appreciate any feedback I can get :)

EDIT: Added some more sensors and holes so I can solder anything to the NodeMCU pins later on.

Improved Schematic enter image description here

Improved PCB enter image description here

Same improved PCB but with an indication of where each component will reside (note: The board at the left will be at the bottom same for the three resistors at the top and the buzzer at the right bottom) enter image description here

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  • \$\begingroup\$ That's fine. I've done very few PCBs and I'm not sure if they're your actual track widths in your lower image. If so they look very thin, particularly the lack of a decent ground line. I don't see any decoupling capacitors but maybe they're on the modules. The board is also very simple and I suspect it could be done with a single-sided board. \$\endgroup\$ – Transistor Aug 24 '19 at 22:16
  • \$\begingroup\$ I've created this schema using a breadboard and the modules without any capacitor, and only have issues when connecting a button for example, which will always result high. I just used the other 3.3V pin on the NodeMCU for it, although a decoupling capacitor would maybe indeed be a better option. They look thin indeed, will check if I can widen it more tomorrow! I rather use a double sided board, as I would like the NodeMCU to be at one side and the components at the other \$\endgroup\$ – Mark D Aug 24 '19 at 22:22
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It would be a good idea to to do a ground pour so that your signals have a low impedance path back. Instead of running ground traces like that. It shouldn't add anything to the cost.

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The PCB looks fine. However, an advice on the track width, use something like this. The width size is decided based on properties like current, copper width, heat etc ....... https://www.4pcb.com/trace-width-calculator.html

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  • \$\begingroup\$ Changed it from 6 to 10, as it could handle the maximum load that will be upon it (0.5A), thanks! \$\endgroup\$ – Mark D Aug 25 '19 at 9:24
  • \$\begingroup\$ Now at 20 mil, which should be plenty \$\endgroup\$ – Mark D Sep 4 '19 at 21:03
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Since you are using through-hole components, I don't see the need for any of the via's that you have. Not that they will cause any issues, but I don't see why you have the NodeMCU connections on the bottom layer and the other modules on the top layer.

I also see that you have SCL and SDA, so you have an I2C interface. Make sure that you have appropriate pull-up resistors for the I2C bus. I won't repeat the other "track width" answer...

The other thing I see is that there are a few DRC errors in your schematic regarding the clearance between the NodeMCU pins and the (I'm guessing) TPlace layer. Depending on who makes your PCB those may be an issue, or not.

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  • \$\begingroup\$ I have them on the bottom and top because I would like to have the sensors facing to the back (so I can later make cutouts for it for in a case), where the NodeMCU should be on the other side so other components could be connected in the near future. I've indeed forgot to add pull-up resistors, but I've added them now, thanks. I have also increased the track width from 6 to 10 mil. I would have to look into the clearance issue, will do! \$\endgroup\$ – Mark D Aug 25 '19 at 9:31
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    \$\begingroup\$ What Ron is saying is that the vias can be done on the component pins, not out in no-man's-land. It reduces the number of holes to drill and plate and this will reduce the number of potential failure points. \$\endgroup\$ – Transistor Aug 25 '19 at 12:43
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Try to avoid sharp trace angles of 90 degrees or less. These can potentially lead to problems with manufacturability.

enter image description here

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  • \$\begingroup\$ Used your feedback, see my latest edit, thanks! \$\endgroup\$ – Mark D Aug 25 '19 at 19:50
  • \$\begingroup\$ @MarkD You missed one near R1 and R2 \$\endgroup\$ – DerStrom8 Aug 25 '19 at 22:41
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    \$\begingroup\$ 90 is absolutely fine, acute should be avoided. Less of a problem than it used to be, but with your very thin traces you might over etch. \$\endgroup\$ – awjlogan Aug 26 '19 at 0:03
  • \$\begingroup\$ 90s are definitely not as much of an issue, but can still cause problems. Notice I didn't mark the 90-degree junctions, just the 90 degree corners. This is because there is more of a chance of a sharp outer corner catching on something and peeling up. \$\endgroup\$ – DerStrom8 Aug 26 '19 at 1:44
  • \$\begingroup\$ @awjlogan I've changed it from 6 mil to 10 mil. Is that still too thin? \$\endgroup\$ – Mark D Aug 26 '19 at 17:19
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I don't see any decoupling capacitors. Be sure that your modules have them close to the sensors.

I think it would be better to have the micro usb of the NodeMCU close to the edge of your PCB so you can plug in and unplug the cable easier. Try to picture the shape of your board, place the components and then start routing.

I'd put an as solid as possible ground pour on the bottom layer. And I'd try to route everything on the top layer, if it is be possible. You can use the bottom layer to make some jumpers using vias. Make the power supply traces a little bigger.

Consider adding some test points if you want to get measurements.

Some traces can be shorter. I know it's a simple board but it will make it look more elegant.

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  • \$\begingroup\$ I will look into the decoupling capacitors. I have not moved it to the edge as the cable needs to bend in a tight space, and some free PCB space could be used for that (no wires running there). I will also look into a ground pour. I decided to route almost everything at the bottom layer, as the bottom layer does not contain many components, thus creating a better overview. I have also widened the traces to be 20 mil wide. What do you think of my improved PCB? \$\endgroup\$ – Mark D Sep 2 '19 at 12:25

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